The purpose of this proposal is to investigate the pathophysiology of exercise-induced asthma. The first set of studies will be concerned with determining if airway cooling alters the activity of adrenergic receptors and/or involves the metabolites of arachidonic acid. The second set are designed to explore whether the time course of the obstructive response to exercise and the refractory period that follows repetitive challenges are related to the endogenous release and subsequent circulation and/or persistence of epinephrine. The third series of investigations will determine why swimming is such a weak stimulus for the development of bronchoconstriction. The final experiments will systematically examine: (1) the factors at work in determining respiratory heat exchange in health and a variety of airway diseases; (2) the effects of thermal environment and drugs upon this; and (3) if patients with airway diseases other than asthma will develop bronchoconstriction in response to airway cooling.